Back-to-Back Pacific Storms to Impact the West Coast; Heavy Snow in the Central Appalachians

Back-to-back powerful Pacific storm systems to impact the Pacific Northwest and northern California through the end of this week with heavy rain, flooding, strong winds, and higher elevation mountain snow. A strong, long-duration atmospheric river will accompany the Pacific storms, bringing excessive rainfall and flash flooding to southwest Oregon and northwest California through the week. Read More >

Spring Frost/Freeze Decision Support Page

Definitions of headlines issued by the National Weather Service in Aberdeen, SD:

Frost Advisory: Issued when conditions are favorable for temperatures to drop between 33 and 36 degrees Fahrenheit resulting in the possibility of widespread frost near the surface. Unprotected vegetation may be damaged.

Freeze Watch: Issued when conditions are favorable for temperatures to drop below 32 degrees Fahrenheit during the next 12 to 48 hours resulting in the possibility for significant damage to unprotected vegetation.

Freeze Warning: Issued when confidence is high that temperatures will drop below 32 degrees Fahrenheit within the next 24 hours resulting in significant damage to unprotected vegetation.

________________________________FORECASTS___________________________________ Click on the images below for the latest forecast temperature information

DAY 1 minimum temp forecast	DAY 2 minimum temp forecast	DAY 3 minimum temp forecast	DAY 4 minimum temp forecast

DAY 5 minimum temp forecast	DAY 6 minimum temp forecast	6-10 Day Temp Outlook	8-14 Day Temp Outlook

_______________________________OBSERVATIONS__________________________________ Find information regarding past and current temperature observations by clicking on the images below

Map display of current temperatures across the region	Map view of the season's last observed 32°/28° temperature across South Dakota	Map view of the season's last observed 32°/28° temperature across Minnesota	Map view of the season's last observed 32°/28° temperature across North Dakota

Table of daily lows at Aberdeen, Watertown, Pierre, Sisseton and Mobridge	Table of daily lows at numerous additional COOP sites

_______________________________CLIMATOLOGY__________________________________ Find climatology information pertaining to frost/freezes by clicking on the images below

Median Date of Last 32° Freeze	Date of Latest Last 32° Freeze	Median Date of Last 28° Freeze	Date of Latest Last 28° Freeze

Interactive map of the average last spring freeze (32° F)	Soil temperature climatology

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The table below presents statistical data regarding the last spring frost/freeze using 1991-2020 data from several NWS COOP sites. "Area" following a location means there have been multiple stations used for the database (within 5 miles of each other). Below are a few examples on how to read the table, using Aberdeen:

Mean: May 9th is the average date when temperatures last drop to 32°F (May 1st for 28°F)
10th: Only 1 in 10 seasons will have a last 32°F freeze on or before April 23rd (April 17th for 28°F)
90th: 9 in 10 seasons will have a last 32°F freeze on or before May 21st (May 15th for 28°F)

SOUTH DAKOTA Spring Freeze Probabilities	Freeze: 32°			Hard Freeze: 28°
*Using 1991-2020 Data*	Mean	10th	90th	Mean	10th	90^th
Aberdeen	5/9	4/23	5/21	5/1	4/17	5/15
Britton	5/5	4/16	5/20	4/26	4/10	5/13
Clark area	5/7	4/22	5/19	4/26	4/10	5/15
Clear Lake	5/4	4/21	5/17	4/23	4/10	5/4
Columbia 8N	5/7	4/17	5/19	4/28	4/13	5/14
Castlewood	5/11	4/26	5/21	5/2	4/17	5/18
Eureka	5/8	4/19	5/20	5/1	4/17	5/15
Faulkton	5/8	4/22	5/20	4/28	4/15	5/15
Gann Valley area	5/11	4/27	5/21	4/30	4/14	5/14
Gettysburg	5/8	4/22	5/18	4/28	4/15	5/14
Highmore	5/12	4/23	5/26	5/6	4/21	5/22
Ipswich	5/10	4/23	5/24	4/30	4/16	5/15
Kennebec	5/11	4/27	5/24	5/4	4/16	5/19
McIntosh 6SE	5/10	4/27	5/21	4/30	4/16	5/15
McLaughlin	5/12	4/26	5/21	5/4	4/19	5/18
Mellette 4W	5/9	4/22	5/20	4/30	4/12	5/16
Milbank area	5/5	4/24	5/15	4/22	4/12	5/7
Miller	5/6	4/20	5/17	4/21	4/11	5/3
Mobridge area	5/8	4/25	5/19	4/29	4/12	5/15
Murdo	5/7	4/20	5/21	4/23	4/10	5/5
Onida 4NW	5/11	4/23	5/24	5/2	5/16	4/17
Pierre	5/7	4/20	5/19	4/25	4/11	5/12
Pollock	5/10	4/24	5/20	5/1	4/16	5/15
Roscoe	5/8	4/20	5/20	4/28	4/11	5/15
Selby	5/12	4/28	5/24	4/29	4/13	5/12
Sisseton area	5/4	4/17	5/16	4/25	4/12	5/12
Summit	5/16	5/2	5/30	5/5	4/18	5/16
Timber Lake	5/11	4/27	5/21	4/30	4/16	5/15
Victor 4NNE	5/3	4/17	5/15	4/21	4/10	5/3
Watertown	5/7	4/23	5/20	4/27	4/16	5/12
Waubay Nat'l Wildlife Refuge	5/3	4/17	5/16	4/21	4/11	4/29
Webster	5/4	4/16	5/16	4/21	4/10	5/3

MINNESOTA Spring Freeze Probabilities	Freeze: 32°			Hard Freeze: 28°
*Using 1991-2020 Data*	Mean	10th	90th	Mean	10th	90th
Artichoke Lake (northeast side)	5/1	4/17	5/14	4/18	4/8	5/2
Wheaton	5/1	4/17	5/13	4/21	4/8	5/4

While records go as far back as 1895 in some cases, the tables above use just a 30 year period, from 1991-2020. Why? 30 years is an internationally agreed upon timeframe to define "Climate Normals," as determined by the World Meteorological Organization back in 1935 because 1.) 30 numbers gives a statistically reliable estimate for an average and 2.) Climate changes over time. To compare what happens today to the entire period of record would be misleading - what's normal today is often very different than what was normal 50 or 100 years ago. Therefore a gradual adjustment is needed to provide context on what climate is like today. This is important for many practical purposes, such as regulation of power companies, crop selection and planting times, construction planning, and other disciplines and industries. You can see how much the climate has changed visually since the 1901-1930 period across the country via maps here.

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Back-to-Back Pacific Storms to Impact the West Coast; Heavy Snow in the Central Appalachians

Spring Frost/Freeze DSS Page